Arduino Uno R4 Due in May With 32-Bit CPU, 16x the RAM and USB-C

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Popular microcontroller gets a major upgrade.

Arduino Uno R4
(Image credit: Arduino)

One of the most popular microcontroller boards around, the Arduino Uno launched all the way back in 2010 and the Uno R3 (revision 3) has been the standard for more than ten years. So it was big news yesterday when, as part of its Arduino Day live stream, the company announced the upcoming Arduino Uno R4 board, which will offer huge leaps forward in processing power, RAM, storage and connectivity.

Due out in May for an as-yet-undisclosed price, the Arduino Uno R4 will be available in both "Minima" (regular) and Wi-Fi versions. The wireless version will have an Espressif S3 module that supports both Wi-Fi and Bluetooth connectivity. 

The Uno R4 will maintain the same pinout and layout as its predecessor but step up to a 32-bit, Renesas RA4M1 CPU running at 48 MHz. That's a huge upgrade from the 8-bit, 16-MHz ATmega328P processor in prior Unos. The new chip is based on the Arm Cortex M4 architecture as opposed to the AVR RISC-based platform on the prior processor. Arduino says that most existing software libraries should work with no modification but a few that were optimized for AVR might need to be tweaked.

The Uno R4 will have 32K of SRAM, which is 16x more than the 2K on the Uno R3. It will also have 256K of onboard NAND versus 32K on the R3. There's a USB-C port for connecting a PC in lieu of the clunky USB Type-B port on older models. The barrel power connector remains in place but can now handle up to 24V instead of 20V. A 12-bit analog DAC, a CAN bus and an SPI port are also on board.

Swipe to scroll horizontally
Arduino Uno R4 vs R3
Header Cell - Column 0 Uno R4Uno R3
CPURenesas RA4M1 (48 MHz, Arm Cortex M4)ATmega328P (16 MHz, AVR)
SRAM32K2K
Flash Storage256K32K
USBType-CType-B
Max Voltage24V20V

In the official photo (shown at the top of this article) of the Uno R4, Arduino has put yellow and green boxes over parts of the PCB. In its broadcast, the company said that it is maintaining an element of surprise and not revealing what's under the boxes until closer to the launch.

If you want to be among the first to buy an Uno R4, you can sign up for the waiting list which will alert you when the board is for sale. There's also an early adopter program for developers who have written popular libraries. If you are accepted into the program, the company will send you a free Uno R4.

While we don't know what the Uno R4 will cost, it seems safe to assume that the Minima version will go for $25 or more as that's what the Uno R3 costs today. The Uno R4 WiFi will obviously be pricier.

The new Uno R4 should be a boon for makers who builds robots or iOT devices with Arduino currently. It will be compatible with a huge ecosystem of shields and other accessories while providing much better performance. 

However, the Uno R4 faces very stiff competition from boards based on Raspberry Pi's RP2040 chip. The RP2040 operates at a generous 133 MHz (about 3x the Uno R4) with dual cores and 256K of SRAM. There are numerous boards with the RP2040 but the first-party Raspberry Pi Pico goes for just $4 for the basic model or $6 with Wi-Fi / Bluetooth.  

On the other hand, the Uno R4 can handle a lot more power than an RP2040 board as its power connector supports up to 24V instead of a mere 5V on Raspberry Pi's platform. We have a detailed comparison of the prior gen Arduino versus Raspberry Pi Pico, which we'll update as soon as we get our hands on the R4.

Avram Piltch
Avram Piltch
Avram Piltch is Tom's Hardware's editor-in-chief. When he's not playing with the latest gadgets at work or putting on VR helmets at trade shows, you'll find him rooting his phone, taking apart his PC or coding plugins. With his technical knowledge and passion for testing, Avram developed many real-world benchmarks, including our laptop battery test.
17 Comments Comment from the forums
  • bit_user
    Price and specs seem noncompetitive with the Raspberry Pi Pico. If you can find them in stock @ list price, the Pi Zero also seems a lot more compelling, unless it's ruled out by power constraints.

    Not that I have hands-on experience with either Arduino or the Pico, but perhaps someone can enlighten me why a newcomer would opt for this instead of the Pi Pico. Are there compatibility issues between the Arduino ecosystem and the Pico?

    Also, I'm reading the Pico's RP2040 is made on a 40 nm process node. Do we know what node the Uno R4's processor uses? It would also be useful to know how power consumption compares, and whether the Pico can be underclocked to match.
    Reply
  • thisisaname
    Looks more like a tease than a produce announcement.

    Also remember power is measured in W(atts) not in V(olts). Being able to handle 24V instead of 20V does not mean it can handle more power, just it can take a voltage.
    Reply
  • Findecanor
    The thing with þe olde AVR was that it is electrically robust, with all pins 5V-tolerant.
    Most ARM Cortex-M based MCUs run on 3.3V and must not get much higher voltage than that.

    According to the RA4M1's datasheet, only nine of its GPIO pins are 5V-tolerant.
    Nice upgrades otherwise though. The proper USB device (not just a programming interface) is a welcome addition.
    Reply
  • palladin9479
    So for those confused, this is something used for industrial and automotive computing, not home user stuff or "can it play crysis" stuff. As such performance isn't really something that's super relevant, instead compatibility, stability and how the board integrates with GPIO and existing platforms. The R4 having the same pinout and practically being a drop in replacement is huge, it means manufacturers don't need to redevelop or port existing firmware or software over to the new board. $25 USD is a minor concern when put in the context of a $24,000 USD car or $100,000 industrial machinery. The 24V power supply gives away it's purpose, 12/24V is standard in automotive and industrial applications, where as 3.3 and 5V are standard in consumer applications.

    Comparing it to the Raspberry PI seems kinda off, different product for a different market segment.
    Reply
  • 1_rick
    bit_user said:
    Price and specs seem noncompetitive with the Raspberry Pi Pico. If you can find them in stock @ list price, the Pi Zero also seems a lot more compelling, unless it's ruled out by power constraints.

    Not that I have hands-on experience with either Arduino or the Pico, but perhaps someone can enlighten me why a newcomer would opt for this instead of the Pi Pico. Are there compatibility issues between the Arduino ecosystem and the Pico?

    Also, I'm reading the Pico's RP2040 is made on a 40 nm process node. Do we know what node the Uno R4's processor uses? It would also be useful to know how power consumption compares, and whether the Pico can be underclocked to match.

    Most of the GPIO pins can handle about 10-20 mA, and there's a 60mA max across all pins.

    Then again, the Renesas is a Cortex M4 with a DSP and an FPU, which I don't think the RP2040 has. It also has a TRNG, which won't matter to everyone. I see from the datasheet it's got a 38x4 LCD controller as well.
    Reply
  • bit_user
    thisisaname said:
    remember power is measured in W(atts) not in V(olts). Being able to handle 24V instead of 20V does not mean it can handle more power, just it can take a voltage.
    I think the assumption is that it'll be able to handle at least the same amount of current. If so, then increasing voltage naturally translates into more power, since W = V * A.
    Reply
  • bit_user
    palladin9479 said:
    this is something used for industrial and automotive computing,
    You you mean Arduino specifically is used for those applications? Or just that it fits in a class of platforms which are used for such purposes? Because I always thought Arduino was aimed more at hobbyists, tinkerers, and students. Automotive-grade means lots of additional certifications and robustness, which naturally translates into higher costs. For the most part, I'd assume it also means using bespoke PCBs and dust/vibration-resistant connectors, which would seem to rule out boards like this.

    palladin9479 said:
    25 USD is a minor concern when put in the context of a $24,000 USD car or $100,000 industrial machinery.
    Are you aware of such examples, or is that just a hypothetical?

    palladin9479 said:
    The 24V power supply gives away it's purpose, 12/24V is standard in automotive and industrial applications,
    And where did 20 V come from?

    palladin9479 said:
    Comparing it to the Raspberry PI seems kinda off, different product for a different market segment.
    The article compared it to the Pico. Are you saying Les Pounder is off the mark in doing so?

    How would you characterize the intended application domain of the Pi Pico, then?

    IMO, the Pi Zero comparison is also somewhat apt, as it has I2C as well. Therefore, can be used for some of the same things, while also providing a lot more compute power and memory, for cases where that's useful. Frankly, I'm at a loss as to why this board costs quite so much.
    Reply
  • bit_user
    1_rick said:
    Most of the GPIO pins can handle about 10-20 mA, and there's a 60mA max across all pins.
    Which does? And how does it compare with the other?

    1_rick said:
    the Renesas is a Cortex M4 with a DSP and an FPU, which I don't think the RP2040 has.
    Ah, good point. The RP2040 has no FPU, but does claim to have an integer divider "peripheral".

    1_rick said:
    It also has a TRNG, which won't matter to everyone.
    By comparison, the RP2040 says the following, of its support for random number generation:
    "If the system clocks are running from the XOSC and/or PLLs the ROSC can be used to generate random numbers. Simply enable the ROSC and read the RANDOMBIT register to get a 1-bit random number and read it n times to get an n-bit value. This does not meet the requirements of randomness for security systems because it can be compromised, but it may be useful in less critical applications."Source: https://datasheets.raspberrypi.com/rp2040/rp2040-datasheet.pdf
    Reply
  • jp7189
    I'll just chime in and say Arduino is popular in the 3D printer space (and other such machines). That space is moving to power supplies with a single 24v rail, and various components are being updated to match. There are a few Pi machines but they are relatively uncommon.

    I would also guess (hope) the R4 has enough processing power to run Delta style machines where previous Arduinos didn't do very well.
    Reply
  • edzieba
    palladin9479 said:
    So for those confused, this is something used for industrial and automotive computing, not home user stuff or "can it play crysis" stuff. As such performance isn't really something that's super relevant, instead compatibility, stability and how the board integrates with GPIO and existing platforms.
    Arduinos are firmly in the hobbyist camp. You would not consider using them in an industrial environment, as they are wholly unsuitable (not sufficiently ruggedised or reliable). They serve the exact same niche as the RP2020.
    The R4 having the same pinout and practically being a drop in replacement is huge, it means manufacturers don't need to redevelop or port existing firmware or software over to the new board. $25 USD is a minor concern when put in the context of a $24,000 USD car or $100,000 industrial machinery. The 24V power supply gives away it's purpose, 12/24V is standard in automotive and industrial applications, where as 3.3 and 5V are standard in consumer applications.
    No car or industrial machine will be using an Arduino. It would be unlikely for them to even be used for prototyping, with devboards for actual industrial SoCs readily available for R&D on the actual platforms to be used- and more importantly the development environment to actually be used.
    Comparing it to the Raspberry PI seems kinda off, different product for a different market segment.
    Arduinos and RPis serve the same market segment: hobbyists. The RPi Compute Module is the closest to something that would find its way into the industrial sector, because the required carrier boards to host it can implement the protections required for that environment.
    Reply